1. Field of Invention
An image processing system and method and, in particular, to a monochromatic image processing system and method of generating look-up tables in real time according to dynamically obtained image pixel data for executing a background removal process.
2. Related Art
In the copy function of a multi-function peripheral (MFP), an image input device such as a scanner first captures the original image for various subsequent images processing before making copies.
Since the retrieval of the original image has some intrinsic problems, e.g., the source document paper is too thin, double side printed, too dirty, etc. or the source document may be extrinsically interfered during the process of capturing the original image; therefore, there may have a problem of smudge noises in the image data obtained by the scanner. If the smudge noises cannot be effectively removed, the image output quality will be seriously affected. Therefore, almost all of MFPs involve similar image processing, i.e., the so-called “background removal process” to remove undesired smudge noises.
The background removal process disclosed in U.S. Pat. No. 5,850,298 is completely implemented by hardware. In the implementation process, histogram data of pixel values obtained by scanning the first source document is used for executing subsequent background removal processes. However, this implementation process has the following drawbacks and problems:
1. The first source document is unable to go through the background removal process. However, in U.S. Pat. No. 5,850,298, the histogram data of pixel values are generated by reading the complete first source document. Therefore, only source documents other than the first source document can be processed with background removal. As a result, the output quality of the source document apparently cannot satisfy the desired standard. This method is of almost useless for a single source document copy mode.
2. It lacks of flexibility in the background removal process for multiple copy modes. Usually, according to the types of source documents, there are several different copy modes, including the text mode, the photo mode, and the auto mode.
In the text mode, all blocks are considered as text blocks for copying. In the photo mode, all blocks are considered as photo blocks for copying. In the auto mode, the blocks are classified into the categories of text, photo, and border blocks for copying.
Different copy modes require different parameters for the background removal process. However, in U.S. Pat. No. 5,850,298, there is no related parameter adjusting mechanism for the background removal process in different copy modes. It does not provide different look-up tables for different copy modes, either. Therefore, in the copy process with multiple source documents, the background removal process effect is very limited if the source documents differ very much in properties.
3. The background removal process structure using completely hardware lacks of flexibility. U.S. Pat. No. 5,850,298 uses purely hardware to implement the background removal process. Since the process of adjusting parameters for different copy modes cannot be very dynamical and the required cost is higher, the flexibility is thus lower, which can't meet the need for future products.
In summary, the existing background removal mechanisms still have many drawbacks. In view of recent progress in hardware and software technologies, it is necessary to provide a new structure to solve the above-mentioned problems and handle processes that cannot be handled by the conventional method. Therefore, the output quality, applications, and flexibility of the background removal process can be greatly improved to satisfy the requirements of product designs.